1. Field of the Invention
The invention relates to a structure in a functional portion in an electrical junction box of a vehicle such as an automobile, the functional portion adapted for guiding an electrical wire, the structure being adapted to prevent displacement of a tape that is wound around the functional portion to secure a wiring harness thereto.
2. Description of the Related Art
Various types of wire-guiding portions have been advocated in the art, the portions being adapted to secure a wiring harness, which may comprise a plurality of electrical wires, to a wire-guiding portion in an electrical junction box by winding a tape around it.
Japanese Patent Application Laid-Open Publication No. 2007-28806 (FIGS. 1 and 2) discloses a state of the art configuration of an electrical junction box that includes a lower case into which a connection block is inserted, the connection block having electrical components such as a fuse and a relay connected thereto. The state of the art electrical junction box further includes an upper case attached to the lower case.
A wire-guiding portion of this conventional junction box is constructed by (a) an inverted gutter-like upper securing piece provided on the connection block and (b) a gutter-like lower securing piece provided on the lower case. The electrical wires each connected to corresponding each of electrical components of the connection block are placed in the form of a wiring harness and inserted into and passed through the space between the upper securing piece and the lower securing piece. The wiring harness is secured by means of winding of a tape to the upper securing piece and the lower securing piece.
In addition to the above example, FIG. 5 illustrates another example of a conventional tape-winding-purpose wire-guiding portion structure. This structure is described in the context of an electrical junction box that comprises a frame 31 accommodating a not-shown connection block and a lower cover 32 attached to the frame 31, and a not-shown upper cover attached to the frame 31.
The frame 31 includes an inverted gutter-like wire-guiding wall 33. The lower cover 32 includes a plate-like wire-supporting wall 34 opposed to the lower portion of the wire-guiding wall 33. At least the outer surface of the wire-guiding wall 34 includes a tape slippage prevention rib 35 that protrudes therefrom. The rib 35 includes the front-side sloping surface 35a and the rear-side tape hooking purpose vertical surface 35b. 
A plurality of electrical wires each continuing to electrical components of the not-shown connection block are placed in the form of a wiring harness, and they are guided to an outside along the wire-guiding portion 36 constituted by the wire-guiding wall 33 and the wire-supporting wall 34. The tape is wound around the wiring harness along the outer surface of the wire-guiding portion 36 and the outer surface of the rib 35 radially thereof, and the wiring harness is secured to the wire-guiding portion 36. Further, the space between the wire-guiding portion 36 and the wiring harness is made waterproof.
In the case of the state of the art tape-displacement-preventing structure for the conventional wire-guiding portion shown in FIG. 5, the rear end face (tape hooking surface) 35b of the tape slippage prevention purpose rib 35 intersects with the outer surface of the wire-guiding wall 33 as indicated by the chained line. Also, the wire-guiding portion 36 is provided obliquely downward.
Accordingly, in cases where large vibration while a vehicle is running acts thereupon or a large pulling force acts upon the wiring harness, the tape may be displaced frontward (toward the edge of the wire-guiding portion 36). Occurrence of the tape displacement decreases the securing force of the wiring harness, and water may enter the inside of the wire-guiding portion 36 via the space created by the displaced wound tape.
In view of the above-identified problem, it can be seen that there is a need to provide a wire-guiding portion with a tape-displacement-preventing structure or feature that allows for effective prevention of tape displacement in the wire-guiding portion due to vibrations and pulling of the wiring harness, and, in addition, effective prevention of the tape displacement even when the wire-guiding portion is arranged obliquely downward.